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Spring and method for producing same

一种制造方法、压缩残余应力的技术，应用在制造工具、涂层、炉子类型等方向，能够解决疲劳强度增加等问题

Inactive Publication Date: 2012-12-19
NHK SPRING CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, there is no description of compressive residual stress in Patent Document 6, and the thickness of the surface high-hardness layer is at most 60 μm. Therefore, it is not expected that the fatigue strength will increase significantly based on the content described in Patent Document 6.

Method used

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  • Spring and method for producing same
  • Spring and method for producing same

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Experimental program
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Embodiment Construction

[0060] A chemical surface treatment was carried out under the conditions shown in Table 2 on the round bar steel material with a diameter of 4 mm containing the representative chemical composition shown in Table 1. However, in order to austenitize reliably, it held at 860 degreeC for 15 minutes as a secondary treatment. Then, it is quenched by cooling to room temperature at a rate of 20° C. / second or more, and then tempered for 60 minutes. Next, shot peening is performed on the tempered round steel bar. In shot peening, a round cut wire (630HV) with a ball equivalent diameter of 0.8mm is used as the first stage, a round cut wire (630HV) with a ball equivalent diameter of 0.45mm is used as the second stage, and a third stage is used. Sand grains with a spherical equivalent diameter of 0.1 mm are used.

[0061] [Table 1]

[0062]

[0063] [Table 2]

[0064]

[0065] Various properties of the steel materials obtained as above were investigated in the following manner. Th...

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PUM

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Abstract

A spring characterized by: having a total composition comprising, in terms of wt%, 0.27-0.48% of C, 0.01-2.2% of Si, 0.30-1.0% of Mn, not more than 0.035% of P, and not more than 0.035% of S, the balance being Fe and inevitable impurities; the thicknesses of a nitrogen compound layer and carbon compound layer on the surface being not more than 2 [mu]m; the hardness at the center part of the cross section being 500-700 HV; a compressive residual stress layer with a thickness of 0.30 mm to D / 4 [wherein D stands for the circle equivalent diameter (mm) of the cross section] being formed in the surface layer; and the maximum compression residual stress thereof being 1400-2000 MPa.

Description

technical field [0001] The present invention relates to a spring and its manufacturing method, and in particular to the technique of forming a layer of high compressive residual stress from the surface to the deep. Background technique [0002] Valve springs for vehicles are aimed at small size and light weight, and since the diameter of the spring wire (plain wire) becomes smaller and the design stress increases, the strength of the wire tends to increase. Therefore, in order to maintain fatigue resistance even under high operating stress, springs require further improvement in fatigue strength, and one solution to this is to form high and deep compressive residual stress in the surface layer of the wire rod. Hitherto, springs have generally formed compressive residual stress on the surface of the wire rod by shot peening. However, with the increase in hardness of the wire rod in recent years, the amount of plastic deformation of the surface layer has decreased, making it d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D1/06C21D7/06C21D9/02C22C38/04C23C8/32
CPCC21D9/02C23C8/80C22C38/02C22C38/04C23C8/32C21D1/06C21D1/25C21D7/06C21D2211/001C21D2211/008
Inventor 铃木健小野芳树黑川真平
Owner NHK SPRING CO LTD